Probability of an El Nino formation in 2017 has led to some worries about India's monsoon season, but exact impact on rains and crop production will not be solely dependent on this event, says a Nomura report.

According to the Australian Bureau of Meteorology (ABM), the likelihood of an El Nino forming in 2017 has risen. Six (out of eight) models surveyed by ABM suggest that El Nino thresholds may be reached by July 2017. It places the probability of El Nino forming in 2017 at around 50 per cent.

"Overall, it does appear that the probability of a below-normal monsoon year in 2017 is higher than the probability of an above-normal year. However, the exact impact (on rains and food production) will depend on several other factors as well," Nomura India Chief Economist Sonal Varma said in a research note.

El Nino is a weather condition, which has a major impact on the Indian monsoon season. A normal monsoon is vital for the country's farming sector as a significant portion of the country's agricultural land is rainfed.

"This has led to some worries about India's monsoon season, which runs from June to September, as El Nino conditions are typically associated with below-normal rains. However, we note that the relationship is not a slam-dunk," the note said.

According to an analysis by Nomura, in the last thirty years when El Nino thresholds were breached during the monsoon season (on average), India witnessed below-normal monsoon only in five occasions (1987, 1991, 2002, 2004, 2015), while on three occasions there was normal monsoon, and in 1994 there was above normal monsoon as well.

Moreover, the timing of El Nino also matters for agriculture. If El Nino happens around July just after the sowing is completed, then the impact on food production would be adverse. However, if the El Nino conditions happen towards the end of August, then the impact may not be as negative.

India's monsoon season starts from June and extends up till September.